Magneto generator



Patented Nov. 10, 1936 PATENT .orrice MAGNET() GENERATORv Walter J. Spengler,

Sidney, N. Y., assigner to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application June 20,

1935, Serial No. 27,475

3 claims. (ci. 1v1- 2.09)

The present invention relates to magneto generators and more particularly to a magneto rotor and the method of making the same.

Magnetic alloys composed principally of aluminum, nickel and iron. have recently been developed which permit the construction of permanent magnets having very high unit coercive force. Advantage has been taken of the magnetic properties of these alloys to construct rotors for ignition magnetos in which the magnets are arcuate in shape and form a ring having projecting pole pieces, no larger in diameter than the conventional magneto rotor using U-shaped. magnets of cobalt or chrome steel.

Permanent magnet alloys are in general too hard for any machining operations other than grinding, so that it is customary to cast the magnets in approximately their nal form and thereafter grind them to size and shape. It has been found that ithe aluminum, nickel and iron alloys of the type above referred to have the property of requiring comparatively little heat treatment subsequent to casting in order to secure the desired magnetic properties.

It is an object of the present invention to utilize the characteristics of the aluminum, nickel, iron alloys in the production of a novel magneto rotor'whiclc is effective in action while simple and rigid in construction.

It 'is another object to provide such a rotor the parts whereof are unied into a single integral structure. y

It is a further object to provide such a device in whichpthe only 'parts requiring any machine work are the shaft and pole pieces which are formed of soft metal.

It is another object to provide such a device in which the pole pieces and shaft are welded to the permanent magnets so as to provide a magnetic path of least resistance and a structure of maximum rigidity.

It is another object of this invention to provide anovel method of constructing a magneto rotor of the above type which is simple, rapid, economical and efficient.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawing in which:

Fig. 1 is a side view partly in vertical section of a preferred embodiment of the invention;

Fig. 2- is a Vertical section taken substantially on the line 2-2 of Fig. 1; and

Fig. 3 isa view similar to Fig. 2 of'a rotor embodying four pole shoes instead of two.

' and the aluminum,

.the shaft and pole pieces,l

cannot cause the rotor Referring to Fig. 1 ci the drawing, there is illustrated a shaft i of conventional form and material which is adapted to be mounted in a magneto frame and rotated by suitable coupling' means, not illustrated since they form no part 5 of the present invention. An intermediate portion of the shaft I is preferably knurled or iluted as illustrated at 2, and a mass of permanent magnetic alloy 3 is cast thereon forming a ring in which soft iron pole pieces 4 are embedded. 10 The pole pieces are preferably bevelled at their ends as indicated at 5 so as to dovetail into the magnet ring 3, and may further be provided with serrations or grooves 6 on their inner surfaces in order to positively interlock with the material l5 of the magnetic ring.

According to the present invention, the rotor is built up by placing theshaft i in a suitable mold with the pole pieces i spaced circumferentially and radially thereabcut. Suitable nur; is then applied to the external surface of the shaft and the internal surfaces of the pole pieces, nickel, iron alloy which has been heated just suillciently to cause it to flow is then poured into the mold so as to surround the shaft and flow into and around the pole pieces. Since the melting point ci the alloy is not greatly removed from the melting points of the surfaces of the shaft and pole pieces are raised to a Welding temperature by the molten alloy whereby upon cooling, the parts are welded together to form an integral unit.

Since the magnetic properties of the aluminum, nickel, iron 'alloy are not destroyed by the cast- 35 ing operation, intensive heat treatment of the rotor to restore its magnetic properties is unnecessary. However, it is within the purview of the present invention to chill the mold immediately subsequent to the casting operation, or even o to re-heat and quench the rotor if such be deemed desirable, and it will be clear that such treatment to disintegrate inasmuch as it has been welded into a completely uniiled structure.

After the rotor has cooled, the magnetic ring is charged by placing the pole pieces 4 thereof in a magnetic circuit of high intensity whereby the permanent magnetic material becomes highly magnetized.

This method of manufacture is equally well adapted for' rotors having two poles 'as illustrated in Fig. 2 ora larger number as shown in Fig. 3, the number of poles and dimensions of the parts being determined by the dimensions and 55 9,080,280 characteristics of the magneto inwhich the rotor pole pieces cireulariy and radially about the is to be incorporated.

shaft, applying flux to the shaft and pole pieces. It will be understood that various changes may be made in the design and dimensions of the parts, and in the prectse steps used in manufacturing the device without departing from the spirit of the invention as denned in the claims appended hereto.

What is claimed is:

1. In a. magneto rotor a shaft, pole pieces ar ranged circumferentially about the shaft, and a said mold to condition the magnetic alloy, and thereafter charging the magnetic ring.

3. In a magneto rotor a shaft. poie pieces arranged circumferentially about the shaft. and a permanent magnet filling the space between the shaft and pole pieces, said shaft and pole pieces form an integral structure. 2. A method of making a magneto rotor oomprising the steps of placing ashaft and a piuraiity of pole pieces in a mold which holds the WALTER J. SPENGLER. 

